1221111020100 has 144 divisors (see below), whose sum is σ = 3616255197632. Its totient is φ = 317968035840.

The previous prime is 1221111020093. The next prime is 1221111020137. The reversal of 1221111020100 is 10201111221.

It is a super-2 number, since 2×1221111020100² (a number of 25 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 55110624 + ... + 55132776.

Almost surely, 2^{1221111020100} is an apocalyptic number.

1221111020100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221111020100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1808127598816).

1221111020100 is an abundant number, since it is smaller than the sum of its proper divisors (2395144177532).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221111020100 is a wasteful number, since it uses less digits than its factorization.

1221111020100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26486 (or 26479 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 1221111020100 its reverse (10201111221), we get a palindrome (1231312131321).

The spelling of 1221111020100 in words is "one trillion, two hundred twenty-one billion, one hundred eleven million, twenty thousand, one hundred".